In recent years, a memory card and equipment which carry a rewritable nonvolatile memory have been spreading. Since the memory card especially has better resistance to vibration, the memory card is expected to be increasingly used.
A flash memory is a typical rewritable nonvolatile memory. Generally, data is written in units of pages and data is erased in units of erase blocks. The erase block ordinary consists of a plurality of the pages. In a following description, the page and erase block are referred to as a block. It is managed in units of blocks whether the flash memory is in use or not in use, for example, “1” is written as management data with respect to a block not in use and when data is written to the block not in use, the management data is changed from “1” to “0”.
Generally, the flash memory fails to write data on rare occasions. For this reasons, the flash memory is provided with a function to read status showing whether data writing is normal writing or abnormal writing. After data writing, it is required to determine by reading this status whether data writing has been normally executed. When writing error occurs, a corresponding management data of a block is changed from “1” to “0” in order not to be selected as a writing block again.
Concerning writing error of the flash memory mentioned above, an art described in Patent document 1 is known.
Patent document 1: Unexamined Patent Publication 2002-108720 (paragraphs 0003 to 0004).